Column Elements and Expressions — SQLAlchemy 0.8 Documentation

# SQLAlchemy 0.8 Documentation

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Release: 0.8.4 | Release Date: December 8, 2013

# Column Elements and Expressions

The most fundamental part of the SQL expression API are the “column elements”, which allow for basic SQL expression support. The core of all SQL expression constructs is the `ClauseElement`, which is the base for several sub-branches. The `ColumnElement` class is the fundamental unit used to construct any kind of typed SQL expression.

`sqlalchemy.sql.expression.` `and_`(*clauses)

  Join a list of clauses together using the `AND` operator.

  The `&` operator is also overloaded on all `ColumnElement` subclasses to produce the same result.

`sqlalchemy.sql.expression.` `asc`(column)

  Return an ascending `ORDER BY` clause element.

  e.g.:

      someselect.order_by(asc(table1.mycol))

  produces:

      ORDER BY mycol ASC

`sqlalchemy.sql.expression.` `between`(ctest, cleft, cright)

  Return a `BETWEEN` predicate clause.

  Equivalent of SQL `clausetest BETWEEN clauseleft AND clauseright`.

  The `between()` method on all `ColumnElement` subclasses provides similar functionality.

`sqlalchemy.sql.expression.` `bindparam`(key, value=<symbol 'NO_ARG>, type_=None, unique=False, required=<symbol 'NO_ARG>, quote=None, callable_=None)

  Create a bind parameter clause with the given key.

  Parameters: | key – the key for this bind param. Will be used in the generated SQL statement for dialects that use named parameters. This value may be modified when part of a compilation operation, if other `BindParameter` objects exist with the same key, or if its length is too long and truncation is required. value – Initial value for this bind param. This value may be overridden by the dictionary of parameters sent to statement compilation/execution. Defaults to `None`, however if neither `value` nor `callable` are passed explicitly, the `required` flag will be set to `True` which has the effect of requiring a value be present when the statement is actually executed. Changed in version 0.8: The `required` flag is set to `True` automatically if `value` or `callable` is not passed. callable_ – A callable function that takes the place of “value”. The function will be called at statement execution time to determine the ultimate value. Used for scenarios where the actual bind value cannot be determined at the point at which the clause construct is created, but embedded bind values are still desirable. type_ – A `TypeEngine` object that will be used to pre-process the value corresponding to this `BindParameter` at execution time. unique – if True, the key name of this BindParamClause will be modified if another `BindParameter` of the same name already has been located within the containing `ClauseElement`. required – If `True`, a value is required at execution time. If not passed, is set to `True` or `False` based on whether or not one of `value` or `callable` were passed.. Changed in version 0.8: If the `required` flag is not specified, it will be set automatically to `True` or `False` depending on whether or not the `value` or `callable` parameters were specified. quote – True if this parameter name requires quoting and is not currently known as a SQLAlchemy reserved word; this currently only applies to the Oracle backend.

`sqlalchemy.sql.expression.` `case`(whens, value=None, else_=None)

  Produce a `CASE` statement.

  whens
    A sequence of pairs, or alternatively a dict, to be translated into “WHEN / THEN” clauses.
  value
    Optional for simple case statements, produces a column expression as in “CASE <expr> WHEN ...”
  else_
    Optional as well, for case defaults produces the “ELSE” portion of the “CASE” statement.

  The expressions used for THEN and ELSE, when specified as strings, will be interpreted as bound values. To specify textual SQL expressions for these, use the `literal_column()` construct.

  The expressions used for the WHEN criterion may only be literal strings when “value” is present, i.e. CASE table.somecol WHEN “x” THEN “y”. Otherwise, literal strings are not accepted in this position, and either the text(<string>) or literal(<string>) constructs must be used to interpret raw string values.

  Usage examples:

      case([(orderline.c.qty > 100, item.c.specialprice),
            (orderline.c.qty > 10, item.c.bulkprice)
          ], else_=item.c.regularprice)
      case(value=emp.c.type, whens={
              'engineer': emp.c.salary * 1.1,
              'manager':  emp.c.salary * 3,
          })

  Using `literal_column()`, to allow for databases that do not support bind parameters in the `then` clause. The type can be specified which determines the type of the `case()` construct overall:

      case([(orderline.c.qty > 100,
              literal_column("'greaterthan100'", String)),
            (orderline.c.qty > 10, literal_column("'greaterthan10'",
              String))
          ], else_=literal_column("'lethan10'", String))

`sqlalchemy.sql.expression.` `cast`(clause, totype, **kwargs)

  Return a `CAST` function.

  Equivalent of SQL `CAST(clause AS totype)`.

  Use with a `TypeEngine` subclass, i.e:

      cast(table.c.unit_price * table.c.qty, Numeric(10,4))

  or:

      cast(table.c.timestamp, DATE)

`sqlalchemy.sql.expression.` `column`(text, type_=None)

  Return a textual column clause, as would be in the columns clause of a `SELECT` statement.

  The object returned is an instance of `ColumnClause`, which represents the “syntactical” portion of the schema-level `Column` object. It is often used directly within `select()` constructs or with lightweight `table()` constructs.

  Note that the `column()` function is not part of the `sqlalchemy` namespace. It must be imported from the `sql` package:

      from sqlalchemy.sql import table, column

  Parameters: | text – the name of the column. Quoting rules will be applied to the clause like any other column name. For textual column constructs that are not to be quoted, use the `literal_column()` function. type_ – an optional `TypeEngine` object which will provide result-set translation for this column.

  See `ColumnClause` for further examples.

`sqlalchemy.sql.expression.` `collate`(expression, collation)

  Return the clause `expression COLLATE collation`.

  e.g.:

      collate(mycolumn, 'utf8_bin')

  produces:

      mycolumn COLLATE utf8_bin

`sqlalchemy.sql.expression.` `desc`(column)

  Return a descending `ORDER BY` clause element.

  e.g.:

      someselect.order_by(desc(table1.mycol))

  produces:

      ORDER BY mycol DESC

`sqlalchemy.sql.expression.` `distinct`(expr)

  Return a `DISTINCT` clause.

  e.g.:

      distinct(a)

  renders:

      DISTINCT a

`sqlalchemy.sql.expression.` `extract`(field, expr)

  Return the clause `extract(field FROM expr)`.

`sqlalchemy.sql.expression.` `false`()

  Return a `False_` object, which compiles to `false`, or the boolean equivalent for the target dialect.

`sqlalchemy.sql.expression.` `func` = <sqlalchemy.sql.expression._FunctionGenerator object at 0x102a77e90>

  Generate SQL function expressions.

  `func` is a special object instance which generates SQL functions based on name-based attributes, e.g.:

      >>> print func.count(1)
      count(:param_1)

  The element is a column-oriented SQL element like any other, and is used in that way:

      >>> print select([func.count(table.c.id)])
      SELECT count(sometable.id) FROM sometable

  Any name can be given to `func`. If the function name is unknown to SQLAlchemy, it will be rendered exactly as is. For common SQL functions which SQLAlchemy is aware of, the name may be interpreted as a generic function which will be compiled appropriately to the target database:

      >>> print func.current_timestamp()
      CURRENT_TIMESTAMP

  To call functions which are present in dot-separated packages, specify them in the same manner:

      >>> print func.stats.yield_curve(5, 10)
      stats.yield_curve(:yield_curve_1, :yield_curve_2)

  SQLAlchemy can be made aware of the return type of functions to enable type-specific lexical and result-based behavior. For example, to ensure that a string-based function returns a Unicode value and is similarly treated as a string in expressions, specify `Unicode` as the type:

      >>> print func.my_string(u'hi', type_=Unicode) + ' ' + \
      ... func.my_string(u'there', type_=Unicode)
      my_string(:my_string_1) || :my_string_2 || my_string(:my_string_3)

  The object returned by a `func` call is usually an instance of `Function`. This object meets the “column” interface, including comparison and labeling functions. The object can also be passed the `execute()` method of a `Connection` or `Engine`, where it will be wrapped inside of a SELECT statement first:

      print connection.execute(func.current_timestamp()).scalar()

  In a few exception cases, the `func` accessor will redirect a name to a built-in expression such as `cast()` or `extract()`, as these names have well-known meaning but are not exactly the same as “functions” from a SQLAlchemy perspective.

  New in version 0.8: `func` can return non-function expression constructs for common quasi-functional names like `cast()` and `extract()`.

  Functions which are interpreted as “generic” functions know how to calculate their return type automatically. For a listing of known generic functions, see SQL and Generic Functions.

`sqlalchemy.sql.expression.` `label`(name, obj)

  Return a `Label` object for the given `ColumnElement`.

  A label changes the name of an element in the columns clause of a `SELECT` statement, typically via the `AS` SQL keyword.

  This functionality is more conveniently available via the `label()` method on `ColumnElement`.

  name
    label name
  obj
    a `ColumnElement`.

`sqlalchemy.sql.expression.` `literal`(value, type_=None)

  Return a literal clause, bound to a bind parameter.

  Literal clauses are created automatically when non- `ClauseElement` objects (such as strings, ints, dates, etc.) are used in a comparison operation with a `ColumnElement` subclass, such as a `Column` object. Use this function to force the generation of a literal clause, which will be created as a `BindParameter` with a bound value.

  Parameters: | value – the value to be bound. Can be any Python object supported by the underlying DB-API, or is translatable via the given type argument. type_ – an optional `TypeEngine` which will provide bind-parameter translation for this literal.

`sqlalchemy.sql.expression.` `literal_column`(text, type_=None)

  Return a textual column expression, as would be in the columns clause of a `SELECT` statement.

  The object returned supports further expressions in the same way as any other column object, including comparison, math and string operations. The type_ parameter is important to determine proper expression behavior (such as, ‘+’ means string concatenation or numerical addition based on the type).

  Parameters: | text – the text of the expression; can be any SQL expression. Quoting rules will not be applied. To specify a column-name expression which should be subject to quoting rules, use the `column()` function. type_ – an optional `TypeEngine` object which will provide result-set translation and additional expression semantics for this column. If left as None the type will be NullType.

`sqlalchemy.sql.expression.` `not_`(clause)

  Return a negation of the given clause, i.e. `NOT(clause)`.

  The `~` operator is also overloaded on all `ColumnElement` subclasses to produce the same result.

`sqlalchemy.sql.expression.` `null`()

  Return a `Null` object, which compiles to `NULL`.

`sqlalchemy.sql.expression.` `nullsfirst`(column)

  Return a NULLS FIRST `ORDER BY` clause element.

  e.g.:

      someselect.order_by(desc(table1.mycol).nullsfirst())

  produces:

      ORDER BY mycol DESC NULLS FIRST

`sqlalchemy.sql.expression.` `nullslast`(column)

  Return a NULLS LAST `ORDER BY` clause element.

  e.g.:

      someselect.order_by(desc(table1.mycol).nullslast())

  produces:

      ORDER BY mycol DESC NULLS LAST

`sqlalchemy.sql.expression.` `or_`(*clauses)

  Join a list of clauses together using the `OR` operator.

  The `|` operator is also overloaded on all `ColumnElement` subclasses to produce the same result.

`sqlalchemy.sql.expression.` `outparam`(key, type_=None)

  Create an ‘OUT’ parameter for usage in functions (stored procedures), for databases which support them.

  The `outparam` can be used like a regular function parameter. The “output” value will be available from the `ResultProxy` object via its `out_parameters` attribute, which returns a dictionary containing the values.

`sqlalchemy.sql.expression.` `over`(func, partition_by=None, order_by=None)

  Produce an OVER clause against a function.

  Used against aggregate or so-called “window” functions, for database backends that support window functions.

  E.g.:

      from sqlalchemy import over
      over(func.row_number(), order_by='x')

  Would produce “ROW_NUMBER() OVER(ORDER BY x)”.

  Parameters: | func – a `FunctionElement` construct, typically generated by `func`. partition_by – a column element or string, or a list of such, that will be used as the PARTITION BY clause of the OVER construct. order_by – a column element or string, or a list of such, that will be used as the ORDER BY clause of the OVER construct.

  This function is also available from the `func` construct itself via the `FunctionElement.over()` method.

  New in version 0.7.

`sqlalchemy.sql.expression.` `text`(text, bind=None, *args, **kwargs)

  Create a SQL construct that is represented by a literal string.

  E.g.:

      t = text("SELECT * FROM users")
      result = connection.execute(t)

  The advantages `text()` provides over a plain string are backend-neutral support for bind parameters, per-statement execution options, as well as bind parameter and result-column typing behavior, allowing SQLAlchemy type constructs to play a role when executing a statement that is specified literally.

  Bind parameters are specified by name, using the format `:name`. E.g.:

      t = text("SELECT * FROM users WHERE id=:user_id")
      result = connection.execute(t, user_id=12)

  To invoke SQLAlchemy typing logic for bind parameters, the `bindparams` list allows specification of `bindparam()` constructs which specify the type for a given name:

      t = text("SELECT id FROM users WHERE updated_at>:updated",
                  bindparams=[bindparam('updated', DateTime())]
              )

  Typing during result row processing is also an important concern. Result column types are specified using the `typemap` dictionary, where the keys match the names of columns. These names are taken from what the DBAPI returns as `cursor.description`:

      t = text("SELECT id, name FROM users",
              typemap={
                  'id':Integer,
                  'name':Unicode
              }
      )

  The `text()` construct is used internally for most cases when a literal string is specified for part of a larger query, such as within `select()`, `update()`, `insert()` or `delete()`. In those cases, the same bind parameter syntax is applied:

      s = select([users.c.id, users.c.name]).where("id=:user_id")
      result = connection.execute(s, user_id=12)

  Using `text()` explicitly usually implies the construction of a full, standalone statement. As such, SQLAlchemy refers to it as an `Executable` object, and it supports the `Executable.execution_options()` method. For example, a `text()` construct that should be subject to “autocommit” can be set explicitly so using the `autocommit` option:

      t = text("EXEC my_procedural_thing()").\
              execution_options(autocommit=True)

  Note that SQLAlchemy’s usual “autocommit” behavior applies to `text()` constructs - that is, statements which begin with a phrase such as `INSERT`, `UPDATE`, `DELETE`, or a variety of other phrases specific to certain backends, will be eligible for autocommit if no transaction is in progress.

  Parameters: | text – the text of the SQL statement to be created. use `:<param>` to specify bind parameters; they will be compiled to their engine-specific format. autocommit – Deprecated. Use .execution_options(autocommit=<True|False>) to set the autocommit option. bind – an optional connection or engine to be used for this text query. bindparams – a list of `bindparam()` instances which can be used to define the types and/or initial values for the bind parameters within the textual statement; the keynames of the bindparams must match those within the text of the statement. The types will be used for pre-processing on bind values. typemap – a dictionary mapping the names of columns represented in the columns clause of a `SELECT` statement to type objects, which will be used to perform post-processing on columns within the result set. This argument applies to any expression that returns result sets.

`sqlalchemy.sql.expression.` `true`()

  Return a `True_` object, which compiles to `true`, or the boolean equivalent for the target dialect.

`sqlalchemy.sql.expression.` `tuple_`(*expr)

  Return a SQL tuple.

  Main usage is to produce a composite IN construct:

      tuple_(table.c.col1, table.c.col2).in_(
          [(1, 2), (5, 12), (10, 19)]
      )

  Warning

  The composite IN construct is not supported by all backends, and is currently known to work on Postgresql and MySQL, but not SQLite. Unsupported backends will raise a subclass of `DBAPIError` when such an expression is invoked.

`sqlalchemy.sql.expression.` `type_coerce`(expr, type_)

  Coerce the given expression into the given type, on the Python side only.

  `type_coerce()` is roughly similar to `cast()`, except no “CAST” expression is rendered - the given type is only applied towards expression typing and against received result values.

  e.g.:

      from sqlalchemy.types import TypeDecorator
      import uuid

      class AsGuid(TypeDecorator):
          impl = String

          def process_bind_param(self, value, dialect):
              if value is not None:
                  return str(value)
              else:
                  return None

          def process_result_value(self, value, dialect):
              if value is not None:
                  return uuid.UUID(value)
              else:
                  return None

      conn.execute(
          select([type_coerce(mytable.c.ident, AsGuid)]).\
                  where(
                      type_coerce(mytable.c.ident, AsGuid) ==
                      uuid.uuid3(uuid.NAMESPACE_URL, 'bar')
                  )
      )

class `sqlalchemy.sql.expression.` `BinaryExpression`(left, right, operator, type_=None, negate=None, modifiers=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent an expression that is `LEFT <operator> RIGHT`.

  A `BinaryExpression` is generated automatically whenever two column expressions are used in a Python binary expresion:

      >>> from sqlalchemy.sql import column
      >>> column('a') + column('b')
      <sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
      >>> print column('a') + column('b')
      a + b

  Inherited-members :

  `compare`(other, **kw)

    Compare this `BinaryExpression` against the given `BinaryExpression`.

class `sqlalchemy.sql.expression.` `BindParameter`(key, value, type_=None, unique=False, callable_=None, isoutparam=False, required=False, quote=None, _compared_to_operator=None, _compared_to_type=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent a bind parameter.

  Public constructor is the `bindparam()` function.

  `__eq__`(other)
    inherited from the `__eq__()` method of `ColumnOperators`

    Implement the `==` operator.

    In a column context, produces the clause `a = b`. If the target is `None`, produces `a IS NULL`.

  `__init__`(key, value, type_=None, unique=False, callable_=None, isoutparam=False, required=False, quote=None, _compared_to_operator=None, _compared_to_type=None)

    Construct a BindParameter.

    Parameters: | key – the key for this bind param. Will be used in the generated SQL statement for dialects that use named parameters. This value may be modified when part of a compilation operation, if other `BindParameter` objects exist with the same key, or if its length is too long and truncation is required. value – Initial value for this bind param. This value may be overridden by the dictionary of parameters sent to statement compilation/execution. callable_ – A callable function that takes the place of “value”. The function will be called at statement execution time to determine the ultimate value. Used for scenarios where the actual bind value cannot be determined at the point at which the clause construct is created, but embedded bind values are still desirable. type_ – A `TypeEngine` object that will be used to pre-process the value corresponding to this `BindParameter` at execution time. unique – if True, the key name of this BindParamClause will be modified if another `BindParameter` of the same name already has been located within the containing `ClauseElement`. quote – True if this parameter name requires quoting and is not currently known as a SQLAlchemy reserved word; this currently only applies to the Oracle backend. required – a value is required at execution time. isoutparam – if True, the parameter should be treated like a stored procedure “OUT” parameter.

  `__le__`(other)
    inherited from the `__le__()` method of `ColumnOperators`

    Implement the `<=` operator.

    In a column context, produces the clause `a <= b`.

  `__lt__`(other)
    inherited from the `__lt__()` method of `ColumnOperators`

    Implement the `<` operator.

    In a column context, produces the clause `a < b`.

  `__ne__`(other)
    inherited from the `__ne__()` method of `ColumnOperators`

    Implement the `!=` operator.

    In a column context, produces the clause `a != b`. If the target is `None`, produces `a IS NOT NULL`.

  `anon_label`
    inherited from the `anon_label` attribute of `ColumnElement`

    provides a constant ‘anonymous label’ for this ColumnElement.

    This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

    the compiler uses this function automatically at compile time for expressions that are known to be ‘unnamed’ like binary expressions and function calls.

  `asc`()
    inherited from the `asc()` method of `ColumnOperators`

    Produce a `asc()` clause against the parent object.

  `between`(cleft, cright)
    inherited from the `between()` method of `ColumnOperators`

    Produce a `between()` clause against the parent object, given the lower and upper range.

  `collate`(collation)
    inherited from the `collate()` method of `ColumnOperators`

    Produce a `collate()` clause against the parent object, given the collation string.

  `compare`(other, **kw)

    Compare this `BindParameter` to the given clause.

  `compile`(bind=None, dialect=None, **kw)
    inherited from the `compile()` method of `ClauseElement`

    Compile this SQL expression.

    The return value is a `Compiled` object. Calling `str()` or `unicode()` on the returned value will yield a string representation of the result. The `Compiled` object also can return a dictionary of bind parameter names and values using the `params` accessor.

    Parameters: | bind – An `Engine` or `Connection` from which a `Compiled` will be acquired. This argument takes precedence over this `ClauseElement`‘s bound engine, if any. column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If `None`, all columns from the target table object are rendered. dialect – A `Dialect` instance from which a `Compiled` will be acquired. This argument takes precedence over the bind argument as well as this `ClauseElement`‘s bound engine, if any. inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

  `concat`(other)
    inherited from the `concat()` method of `ColumnOperators`

    Implement the ‘concat’ operator.

    In a column context, produces the clause `a || b`, or uses the `concat()` operator on MySQL.

  `contains`(other, **kwargs)
    inherited from the `contains()` method of `ColumnOperators`

    Implement the ‘contains’ operator.

    In a column context, produces the clause `LIKE '%<other>%'`

  `desc`()
    inherited from the `desc()` method of `ColumnOperators`

    Produce a `desc()` clause against the parent object.

  `distinct`()
    inherited from the `distinct()` method of `ColumnOperators`

    Produce a `distinct()` clause against the parent object.

  `effective_value`

    Return the value of this bound parameter, taking into account if the `callable` parameter was set.

    The `callable` value will be evaluated and returned if present, else `value`.

  `endswith`(other, **kwargs)
    inherited from the `endswith()` method of `ColumnOperators`

    Implement the ‘endswith’ operator.

    In a column context, produces the clause `LIKE '%<other>'`

  `expression`
    inherited from the `expression` attribute of `ColumnElement`

    Return a column expression.

    Part of the inspection interface; returns self.

  `get_children`(**kwargs)
    inherited from the `get_children()` method of `ClauseElement`

    Return immediate child elements of this `ClauseElement`.

    This is used for visit traversal.

    **kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

  `ilike`(other, escape=None)
    inherited from the `ilike()` method of `ColumnOperators`

    Implement the `ilike` operator.

    In a column context, produces the clause `a ILIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.ilike("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.ilike("foo/%bar", escape="/")

    See also

    `ColumnOperators.like()`

  `in_`(other)
    inherited from the `in_()` method of `ColumnOperators`

    Implement the `in` operator.

    In a column context, produces the clause `a IN other`. “other” may be a tuple/list of column expressions, or a `select()` construct.

  `is_`(other)
    inherited from the `is_()` method of `ColumnOperators`

    Implement the `IS` operator.

    Normally, `IS` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.isnot()`

  `isnot`(other)
    inherited from the `isnot()` method of `ColumnOperators`

    Implement the `IS NOT` operator.

    Normally, `IS NOT` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS NOT` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.is_()`

  `label`(name)
    inherited from the `label()` method of `ColumnElement`

    Produce a column label, i.e. `<columnname> AS <name>`.

    This is a shortcut to the `label()` function.

    if ‘name’ is None, an anonymous label name will be generated.

  `like`(other, escape=None)
    inherited from the `like()` method of `ColumnOperators`

    Implement the `like` operator.

    In a column context, produces the clause `a LIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.like("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.like("foo/%bar", escape="/")

    See also

    `ColumnOperators.ilike()`

  `match`(other, **kwargs)
    inherited from the `match()` method of `ColumnOperators`

    Implements the ‘match’ operator.

    In a column context, this produces a MATCH clause, i.e. `MATCH '<other>'`. The allowed contents of `other` are database backend specific.

  `notilike`(other, escape=None)
    inherited from the `notilike()` method of `ColumnOperators`

    implement the `NOT ILIKE` operator.

    This is equivalent to using negation with `ColumnOperators.ilike()`, i.e. `~x.ilike(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.ilike()`

  `notin_`(other)
    inherited from the `notin_()` method of `ColumnOperators`

    implement the `NOT IN` operator.

    This is equivalent to using negation with `ColumnOperators.in_()`, i.e. `~x.in_(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.in_()`

  `notlike`(other, escape=None)
    inherited from the `notlike()` method of `ColumnOperators`

    implement the `NOT LIKE` operator.

    This is equivalent to using negation with `ColumnOperators.like()`, i.e. `~x.like(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.like()`

  `nullsfirst`()
    inherited from the `nullsfirst()` method of `ColumnOperators`

    Produce a `nullsfirst()` clause against the parent object.

  `nullslast`()
    inherited from the `nullslast()` method of `ColumnOperators`

    Produce a `nullslast()` clause against the parent object.

  `op`(opstring, precedence=0)
    inherited from the `op()` method of `Operators`

    produce a generic operator function.

    e.g.:

        somecolumn.op("*")(5)

    produces:

        somecolumn * 5

    This function can also be used to make bitwise operators explicit. For example:

        somecolumn.op('&')(0xff)

    is a bitwise AND of the value in `somecolumn`.

    Parameters: | operator – a string which will be output as the infix operator between this element and the expression passed to the generated function. precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of `0` is lower than all operators except for the comma (`,`) and `AS` operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators. New in version 0.8: - added the ‘precedence’ argument.

    See also

    Redefining and Creating New Operators

  `params`(*optionaldict, **kwargs)
    inherited from the `params()` method of `ClauseElement`

    Return a copy with `bindparam()` elements replaced.

    Returns a copy of this ClauseElement with `bindparam()` elements replaced with values taken from the given dictionary:

        >>> clause = column('x') + bindparam('foo')
        >>> print clause.compile().params
        {'foo':None}
        >>> print clause.params({'foo':7}).compile().params
        {'foo':7}

  `self_group`(against=None)
    inherited from the `self_group()` method of `ClauseElement`

    Apply a ‘grouping’ to this `ClauseElement`.

    This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by `select()` constructs when placed into the FROM clause of another `select()`. (Note that subqueries should be normally created using the `Select.alias()` method, as many platforms require nested SELECT statements to be named).

    As expressions are composed together, the application of `self_group()` is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like `x OR (y AND z)` - AND takes precedence over OR.

    The base `self_group()` method of `ClauseElement` just returns self.

  `shares_lineage`(othercolumn)
    inherited from the `shares_lineage()` method of `ColumnElement`

    Return True if the given `ColumnElement` has a common ancestor to this `ColumnElement`.

  `startswith`(other, **kwargs)
    inherited from the `startswith()` method of `ColumnOperators`

    Implement the `startwith` operator.

    In a column context, produces the clause `LIKE '<other>%'`

  `unique_params`(*optionaldict, **kwargs)
    inherited from the `unique_params()` method of `ClauseElement`

    Return a copy with `bindparam()` elements replaced.

    Same functionality as `params()`, except adds unique=True to affected bind parameters so that multiple statements can be used.

class `sqlalchemy.sql.expression.` `Case`(whens, value=None, else_=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

class `sqlalchemy.sql.expression.` `Cast`(clause, totype, **kwargs)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

class `sqlalchemy.sql.expression.` `ClauseElement`

  Bases: `sqlalchemy.sql.visitors.Visitable`

  Base class for elements of a programmatically constructed SQL expression.

  `compare`(other, **kw)

    Compare this ClauseElement to the given ClauseElement.

    Subclasses should override the default behavior, which is a straight identity comparison.

    **kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison. (see `ColumnElement`)

  `compile`(bind=None, dialect=None, **kw)

    Compile this SQL expression.

    The return value is a `Compiled` object. Calling `str()` or `unicode()` on the returned value will yield a string representation of the result. The `Compiled` object also can return a dictionary of bind parameter names and values using the `params` accessor.

    Parameters: | bind – An `Engine` or `Connection` from which a `Compiled` will be acquired. This argument takes precedence over this `ClauseElement`‘s bound engine, if any. column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If `None`, all columns from the target table object are rendered. dialect – A `Dialect` instance from which a `Compiled` will be acquired. This argument takes precedence over the bind argument as well as this `ClauseElement`‘s bound engine, if any. inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

  `get_children`(**kwargs)

    Return immediate child elements of this `ClauseElement`.

    This is used for visit traversal.

    **kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

  `params`(*optionaldict, **kwargs)

    Return a copy with `bindparam()` elements replaced.

    Returns a copy of this ClauseElement with `bindparam()` elements replaced with values taken from the given dictionary:

        >>> clause = column('x') + bindparam('foo')
        >>> print clause.compile().params
        {'foo':None}
        >>> print clause.params({'foo':7}).compile().params
        {'foo':7}

  `self_group`(against=None)

    Apply a ‘grouping’ to this `ClauseElement`.

    This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by `select()` constructs when placed into the FROM clause of another `select()`. (Note that subqueries should be normally created using the `Select.alias()` method, as many platforms require nested SELECT statements to be named).

    As expressions are composed together, the application of `self_group()` is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like `x OR (y AND z)` - AND takes precedence over OR.

    The base `self_group()` method of `ClauseElement` just returns self.

  `unique_params`(*optionaldict, **kwargs)

    Return a copy with `bindparam()` elements replaced.

    Same functionality as `params()`, except adds unique=True to affected bind parameters so that multiple statements can be used.

class `sqlalchemy.sql.expression.` `ClauseList`(*clauses, **kwargs)

  Bases: `sqlalchemy.sql.expression.ClauseElement`

  Describe a list of clauses, separated by an operator.

  By default, is comma-separated, such as a column listing.

  `compare`(other, **kw)

    Compare this `ClauseList` to the given `ClauseList`, including a comparison of all the clause items.

class `sqlalchemy.sql.expression.` `ColumnClause`(text, selectable=None, type_=None, is_literal=False)

  Bases: `sqlalchemy.sql.expression.Immutable`, `sqlalchemy.sql.expression.ColumnElement`

  Represents a generic column expression from any textual string.

  This includes columns associated with tables, aliases and select statements, but also any arbitrary text. May or may not be bound to an underlying `Selectable`.

  `ColumnClause` is constructed by itself typically via the `column()` function. It may be placed directly into constructs such as `select()` constructs:

      from sqlalchemy.sql import column, select

      c1, c2 = column("c1"), column("c2")
      s = select([c1, c2]).where(c1==5)

  There is also a variant on `column()` known as `literal_column()` - the difference is that in the latter case, the string value is assumed to be an exact expression, rather than a column name, so that no quoting rules or similar are applied:

      from sqlalchemy.sql import literal_column, select

      s = select([literal_column("5 + 7")])

  `ColumnClause` can also be used in a table-like fashion by combining the `column()` function with the `table()` function, to produce a “lightweight” form of table metadata:

      from sqlalchemy.sql import table, column

      user = table("user",
              column("id"),
              column("name"),
              column("description"),
      )

  The above construct can be created in an ad-hoc fashion and is not associated with any `schema.MetaData`, unlike it’s more full fledged `schema.Table` counterpart.

  Parameters: | text – the text of the element. selectable – parent selectable. type – `types.TypeEngine` object which can associate this `ColumnClause` with a type. is_literal – if True, the `ColumnClause` is assumed to be an exact expression that will be delivered to the output with no quoting rules applied regardless of case sensitive settings. the `literal_column()` function is usually used to create such a `ColumnClause`.

  `__eq__`(other)
    inherited from the `__eq__()` method of `ColumnOperators`

    Implement the `==` operator.

    In a column context, produces the clause `a = b`. If the target is `None`, produces `a IS NULL`.

  `__le__`(other)
    inherited from the `__le__()` method of `ColumnOperators`

    Implement the `<=` operator.

    In a column context, produces the clause `a <= b`.

  `__lt__`(other)
    inherited from the `__lt__()` method of `ColumnOperators`

    Implement the `<` operator.

    In a column context, produces the clause `a < b`.

  `__ne__`(other)
    inherited from the `__ne__()` method of `ColumnOperators`

    Implement the `!=` operator.

    In a column context, produces the clause `a != b`. If the target is `None`, produces `a IS NOT NULL`.

  `anon_label`
    inherited from the `anon_label` attribute of `ColumnElement`

    provides a constant ‘anonymous label’ for this ColumnElement.

    This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

    the compiler uses this function automatically at compile time for expressions that are known to be ‘unnamed’ like binary expressions and function calls.

  `asc`()
    inherited from the `asc()` method of `ColumnOperators`

    Produce a `asc()` clause against the parent object.

  `between`(cleft, cright)
    inherited from the `between()` method of `ColumnOperators`

    Produce a `between()` clause against the parent object, given the lower and upper range.

  `collate`(collation)
    inherited from the `collate()` method of `ColumnOperators`

    Produce a `collate()` clause against the parent object, given the collation string.

  `compare`(other, use_proxies=False, equivalents=None, **kw)
    inherited from the `compare()` method of `ColumnElement`

    Compare this ColumnElement to another.

    Special arguments understood:

    Parameters: | use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage()) equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

  `compile`(bind=None, dialect=None, **kw)
    inherited from the `compile()` method of `ClauseElement`

    Compile this SQL expression.

    The return value is a `Compiled` object. Calling `str()` or `unicode()` on the returned value will yield a string representation of the result. The `Compiled` object also can return a dictionary of bind parameter names and values using the `params` accessor.

    Parameters: | bind – An `Engine` or `Connection` from which a `Compiled` will be acquired. This argument takes precedence over this `ClauseElement`‘s bound engine, if any. column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If `None`, all columns from the target table object are rendered. dialect – A `Dialect` instance from which a `Compiled` will be acquired. This argument takes precedence over the bind argument as well as this `ClauseElement`‘s bound engine, if any. inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

  `concat`(other)
    inherited from the `concat()` method of `ColumnOperators`

    Implement the ‘concat’ operator.

    In a column context, produces the clause `a || b`, or uses the `concat()` operator on MySQL.

  `contains`(other, **kwargs)
    inherited from the `contains()` method of `ColumnOperators`

    Implement the ‘contains’ operator.

    In a column context, produces the clause `LIKE '%<other>%'`

  `desc`()
    inherited from the `desc()` method of `ColumnOperators`

    Produce a `desc()` clause against the parent object.

  `distinct`()
    inherited from the `distinct()` method of `ColumnOperators`

    Produce a `distinct()` clause against the parent object.

  `endswith`(other, **kwargs)
    inherited from the `endswith()` method of `ColumnOperators`

    Implement the ‘endswith’ operator.

    In a column context, produces the clause `LIKE '%<other>'`

  `expression`
    inherited from the `expression` attribute of `ColumnElement`

    Return a column expression.

    Part of the inspection interface; returns self.

  `get_children`(**kwargs)
    inherited from the `get_children()` method of `ClauseElement`

    Return immediate child elements of this `ClauseElement`.

    This is used for visit traversal.

    **kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

  `ilike`(other, escape=None)
    inherited from the `ilike()` method of `ColumnOperators`

    Implement the `ilike` operator.

    In a column context, produces the clause `a ILIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.ilike("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.ilike("foo/%bar", escape="/")

    See also

    `ColumnOperators.like()`

  `in_`(other)
    inherited from the `in_()` method of `ColumnOperators`

    Implement the `in` operator.

    In a column context, produces the clause `a IN other`. “other” may be a tuple/list of column expressions, or a `select()` construct.

  `is_`(other)
    inherited from the `is_()` method of `ColumnOperators`

    Implement the `IS` operator.

    Normally, `IS` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.isnot()`

  `isnot`(other)
    inherited from the `isnot()` method of `ColumnOperators`

    Implement the `IS NOT` operator.

    Normally, `IS NOT` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS NOT` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.is_()`

  `label`(name)
    inherited from the `label()` method of `ColumnElement`

    Produce a column label, i.e. `<columnname> AS <name>`.

    This is a shortcut to the `label()` function.

    if ‘name’ is None, an anonymous label name will be generated.

  `like`(other, escape=None)
    inherited from the `like()` method of `ColumnOperators`

    Implement the `like` operator.

    In a column context, produces the clause `a LIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.like("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.like("foo/%bar", escape="/")

    See also

    `ColumnOperators.ilike()`

  `match`(other, **kwargs)
    inherited from the `match()` method of `ColumnOperators`

    Implements the ‘match’ operator.

    In a column context, this produces a MATCH clause, i.e. `MATCH '<other>'`. The allowed contents of `other` are database backend specific.

  `notilike`(other, escape=None)
    inherited from the `notilike()` method of `ColumnOperators`

    implement the `NOT ILIKE` operator.

    This is equivalent to using negation with `ColumnOperators.ilike()`, i.e. `~x.ilike(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.ilike()`

  `notin_`(other)
    inherited from the `notin_()` method of `ColumnOperators`

    implement the `NOT IN` operator.

    This is equivalent to using negation with `ColumnOperators.in_()`, i.e. `~x.in_(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.in_()`

  `notlike`(other, escape=None)
    inherited from the `notlike()` method of `ColumnOperators`

    implement the `NOT LIKE` operator.

    This is equivalent to using negation with `ColumnOperators.like()`, i.e. `~x.like(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.like()`

  `nullsfirst`()
    inherited from the `nullsfirst()` method of `ColumnOperators`

    Produce a `nullsfirst()` clause against the parent object.

  `nullslast`()
    inherited from the `nullslast()` method of `ColumnOperators`

    Produce a `nullslast()` clause against the parent object.

  `op`(opstring, precedence=0)
    inherited from the `op()` method of `Operators`

    produce a generic operator function.

    e.g.:

        somecolumn.op("*")(5)

    produces:

        somecolumn * 5

    This function can also be used to make bitwise operators explicit. For example:

        somecolumn.op('&')(0xff)

    is a bitwise AND of the value in `somecolumn`.

    Parameters: | operator – a string which will be output as the infix operator between this element and the expression passed to the generated function. precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of `0` is lower than all operators except for the comma (`,`) and `AS` operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators. New in version 0.8: - added the ‘precedence’ argument.

    See also

    Redefining and Creating New Operators

  `self_group`(against=None)
    inherited from the `self_group()` method of `ClauseElement`

    Apply a ‘grouping’ to this `ClauseElement`.

    This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by `select()` constructs when placed into the FROM clause of another `select()`. (Note that subqueries should be normally created using the `Select.alias()` method, as many platforms require nested SELECT statements to be named).

    As expressions are composed together, the application of `self_group()` is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like `x OR (y AND z)` - AND takes precedence over OR.

    The base `self_group()` method of `ClauseElement` just returns self.

  `shares_lineage`(othercolumn)
    inherited from the `shares_lineage()` method of `ColumnElement`

    Return True if the given `ColumnElement` has a common ancestor to this `ColumnElement`.

  `startswith`(other, **kwargs)
    inherited from the `startswith()` method of `ColumnOperators`

    Implement the `startwith` operator.

    In a column context, produces the clause `LIKE '<other>%'`

class `sqlalchemy.sql.expression.` `ColumnCollection`(*cols)

  Bases: `sqlalchemy.util._collections.OrderedProperties`

  An ordered dictionary that stores a list of ColumnElement instances.

  Overrides the `__eq__()` method to produce SQL clauses between sets of correlated columns.

  `add`(column)

    Add a column to this collection.

    The key attribute of the column will be used as the hash key for this dictionary.

  `replace`(column)

    add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.

    > e.g.:

    >     t = Table('sometable', metadata, Column('col1', Integer))
    >     t.columns.replace(Column('col1', Integer, key='columnone'))

    > will remove the original ‘col1’ from the collection, and add the new column under the name ‘columnname’.

    Used by schema.Column to override columns during table reflection.

class `sqlalchemy.sql.expression.` `ColumnElement`

  Bases: `sqlalchemy.sql.expression.ClauseElement`, `sqlalchemy.sql.operators.ColumnOperators`

  Represent a column-oriented SQL expression suitable for usage in the “columns” clause, WHERE clause etc. of a statement.

  While the most familiar kind of `ColumnElement` is the `Column` object, `ColumnElement` serves as the basis for any unit that may be present in a SQL expression, including the expressions themselves, SQL functions, bound parameters, literal expressions, keywords such as `NULL`, etc. `ColumnElement` is the ultimate base class for all such elements.

  A `ColumnElement` provides the ability to generate new `ColumnElement` objects using Python expressions. This means that Python operators such as `==`, `!=` and `<` are overloaded to mimic SQL operations, and allow the instantiation of further `ColumnElement` instances which are composed from other, more fundamental `ColumnElement` objects. For example, two `ColumnClause` objects can be added together with the addition operator `+` to produce a `BinaryExpression`. Both `ColumnClause` and `BinaryExpression` are subclasses of `ColumnElement`:

      >>> from sqlalchemy.sql import column
      >>> column('a') + column('b')
      <sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
      >>> print column('a') + column('b')
      a + b

  `ColumnElement` supports the ability to be a proxy element, which indicates that the `ColumnElement` may be associated with a `Selectable` which was derived from another `Selectable`. An example of a “derived” `Selectable` is an `Alias` of a `Table`. For the ambitious, an in-depth discussion of this concept can be found at Expression Transformations.

  `__eq__`(other)
    inherited from the `__eq__()` method of `ColumnOperators`

    Implement the `==` operator.

    In a column context, produces the clause `a = b`. If the target is `None`, produces `a IS NULL`.

  `__init__`
    inherited from the `__init__` attribute of `object`

    x.__init__(...) initializes x; see help(type(x)) for signature

  `__le__`(other)
    inherited from the `__le__()` method of `ColumnOperators`

    Implement the `<=` operator.

    In a column context, produces the clause `a <= b`.

  `__lt__`(other)
    inherited from the `__lt__()` method of `ColumnOperators`

    Implement the `<` operator.

    In a column context, produces the clause `a < b`.

  `__ne__`(other)
    inherited from the `__ne__()` method of `ColumnOperators`

    Implement the `!=` operator.

    In a column context, produces the clause `a != b`. If the target is `None`, produces `a IS NOT NULL`.

  `anon_label`

    provides a constant ‘anonymous label’ for this ColumnElement.

    This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

    the compiler uses this function automatically at compile time for expressions that are known to be ‘unnamed’ like binary expressions and function calls.

  `asc`()
    inherited from the `asc()` method of `ColumnOperators`

    Produce a `asc()` clause against the parent object.

  `base_columns`
  `between`(cleft, cright)
    inherited from the `between()` method of `ColumnOperators`

    Produce a `between()` clause against the parent object, given the lower and upper range.

  `bind` = None
  `collate`(collation)
    inherited from the `collate()` method of `ColumnOperators`

    Produce a `collate()` clause against the parent object, given the collation string.

  `comparator`
  `compare`(other, use_proxies=False, equivalents=None, **kw)

    Compare this ColumnElement to another.

    Special arguments understood:

    Parameters: | use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage()) equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

  `compile`(bind=None, dialect=None, **kw)
    inherited from the `compile()` method of `ClauseElement`

    Compile this SQL expression.

    The return value is a `Compiled` object. Calling `str()` or `unicode()` on the returned value will yield a string representation of the result. The `Compiled` object also can return a dictionary of bind parameter names and values using the `params` accessor.

    Parameters: | bind – An `Engine` or `Connection` from which a `Compiled` will be acquired. This argument takes precedence over this `ClauseElement`‘s bound engine, if any. column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If `None`, all columns from the target table object are rendered. dialect – A `Dialect` instance from which a `Compiled` will be acquired. This argument takes precedence over the bind argument as well as this `ClauseElement`‘s bound engine, if any. inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

  `concat`(other)
    inherited from the `concat()` method of `ColumnOperators`

    Implement the ‘concat’ operator.

    In a column context, produces the clause `a || b`, or uses the `concat()` operator on MySQL.

  `contains`(other, **kwargs)
    inherited from the `contains()` method of `ColumnOperators`

    Implement the ‘contains’ operator.

    In a column context, produces the clause `LIKE '%<other>%'`

  `desc`()
    inherited from the `desc()` method of `ColumnOperators`

    Produce a `desc()` clause against the parent object.

  `distinct`()
    inherited from the `distinct()` method of `ColumnOperators`

    Produce a `distinct()` clause against the parent object.

  `endswith`(other, **kwargs)
    inherited from the `endswith()` method of `ColumnOperators`

    Implement the ‘endswith’ operator.

    In a column context, produces the clause `LIKE '%<other>'`

  `expression`

    Return a column expression.

    Part of the inspection interface; returns self.

  `foreign_keys` = []
  `get_children`(**kwargs)
    inherited from the `get_children()` method of `ClauseElement`

    Return immediate child elements of this `ClauseElement`.

    This is used for visit traversal.

    **kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

  `ilike`(other, escape=None)
    inherited from the `ilike()` method of `ColumnOperators`

    Implement the `ilike` operator.

    In a column context, produces the clause `a ILIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.ilike("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.ilike("foo/%bar", escape="/")

    See also

    `ColumnOperators.like()`

  `in_`(other)
    inherited from the `in_()` method of `ColumnOperators`

    Implement the `in` operator.

    In a column context, produces the clause `a IN other`. “other” may be a tuple/list of column expressions, or a `select()` construct.

  `is_`(other)
    inherited from the `is_()` method of `ColumnOperators`

    Implement the `IS` operator.

    Normally, `IS` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.isnot()`

  `is_clause_element` = True
  `is_selectable` = False
  `isnot`(other)
    inherited from the `isnot()` method of `ColumnOperators`

    Implement the `IS NOT` operator.

    Normally, `IS NOT` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS NOT` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.is_()`

  `label`(name)

    Produce a column label, i.e. `<columnname> AS <name>`.

    This is a shortcut to the `label()` function.

    if ‘name’ is None, an anonymous label name will be generated.

  `like`(other, escape=None)
    inherited from the `like()` method of `ColumnOperators`

    Implement the `like` operator.

    In a column context, produces the clause `a LIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.like("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.like("foo/%bar", escape="/")

    See also

    `ColumnOperators.ilike()`

  `match`(other, **kwargs)
    inherited from the `match()` method of `ColumnOperators`

    Implements the ‘match’ operator.

    In a column context, this produces a MATCH clause, i.e. `MATCH '<other>'`. The allowed contents of `other` are database backend specific.

  `notilike`(other, escape=None)
    inherited from the `notilike()` method of `ColumnOperators`

    implement the `NOT ILIKE` operator.

    This is equivalent to using negation with `ColumnOperators.ilike()`, i.e. `~x.ilike(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.ilike()`

  `notin_`(other)
    inherited from the `notin_()` method of `ColumnOperators`

    implement the `NOT IN` operator.

    This is equivalent to using negation with `ColumnOperators.in_()`, i.e. `~x.in_(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.in_()`

  `notlike`(other, escape=None)
    inherited from the `notlike()` method of `ColumnOperators`

    implement the `NOT LIKE` operator.

    This is equivalent to using negation with `ColumnOperators.like()`, i.e. `~x.like(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.like()`

  `nullsfirst`()
    inherited from the `nullsfirst()` method of `ColumnOperators`

    Produce a `nullsfirst()` clause against the parent object.

  `nullslast`()
    inherited from the `nullslast()` method of `ColumnOperators`

    Produce a `nullslast()` clause against the parent object.

  `op`(opstring, precedence=0)
    inherited from the `op()` method of `Operators`

    produce a generic operator function.

    e.g.:

        somecolumn.op("*")(5)

    produces:

        somecolumn * 5

    This function can also be used to make bitwise operators explicit. For example:

        somecolumn.op('&')(0xff)

    is a bitwise AND of the value in `somecolumn`.

    Parameters: | operator – a string which will be output as the infix operator between this element and the expression passed to the generated function. precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of `0` is lower than all operators except for the comma (`,`) and `AS` operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators. New in version 0.8: - added the ‘precedence’ argument.

    See also

    Redefining and Creating New Operators

  `operate`(op, *other, **kwargs)
  `params`(*optionaldict, **kwargs)
    inherited from the `params()` method of `ClauseElement`

    Return a copy with `bindparam()` elements replaced.

    Returns a copy of this ClauseElement with `bindparam()` elements replaced with values taken from the given dictionary:

        >>> clause = column('x') + bindparam('foo')
        >>> print clause.compile().params
        {'foo':None}
        >>> print clause.params({'foo':7}).compile().params
        {'foo':7}

  `primary_key` = False
  `proxy_set`
  `quote` = None
  `reverse_operate`(op, other, **kwargs)
  `self_group`(against=None)
    inherited from the `self_group()` method of `ClauseElement`

    Apply a ‘grouping’ to this `ClauseElement`.

    This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by `select()` constructs when placed into the FROM clause of another `select()`. (Note that subqueries should be normally created using the `Select.alias()` method, as many platforms require nested SELECT statements to be named).

    As expressions are composed together, the application of `self_group()` is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like `x OR (y AND z)` - AND takes precedence over OR.

    The base `self_group()` method of `ClauseElement` just returns self.

  `shares_lineage`(othercolumn)

    Return True if the given `ColumnElement` has a common ancestor to this `ColumnElement`.

  `startswith`(other, **kwargs)
    inherited from the `startswith()` method of `ColumnOperators`

    Implement the `startwith` operator.

    In a column context, produces the clause `LIKE '<other>%'`

  `supports_execution` = False
  `timetuple` = None
  `type`
  `unique_params`(*optionaldict, **kwargs)
    inherited from the `unique_params()` method of `ClauseElement`

    Return a copy with `bindparam()` elements replaced.

    Same functionality as `params()`, except adds unique=True to affected bind parameters so that multiple statements can be used.

class `sqlalchemy.sql.operators.` `ColumnOperators`

  Bases: `sqlalchemy.sql.operators.Operators`

  Defines boolean, comparison, and other operators for `ColumnElement` expressions.

  By default, all methods call down to `operate()` or `reverse_operate()`, passing in the appropriate operator function from the Python builtin `operator` module or a SQLAlchemy-specific operator function from `sqlalchemy.expression.operators`. For example the `__eq__` function:

      def __eq__(self, other):
          return self.operate(operators.eq, other)

  Where `operators.eq` is essentially:

      def eq(a, b):
          return a == b

  The core column expression unit `ColumnElement` overrides `Operators.operate()` and others to return further `ColumnElement` constructs, so that the `==` operation above is replaced by a clause construct.

  See also:

  Redefining and Creating New Operators

  `TypeEngine.comparator_factory`

  `ColumnOperators`

  `PropComparator`

  `__add__`(other)

    Implement the `+` operator.

    In a column context, produces the clause `a + b` if the parent object has non-string affinity. If the parent object has a string affinity, produces the concatenation operator, `a || b` - see `ColumnOperators.concat()`.

  `__and__`(other)
    inherited from the `__and__()` method of `Operators`

    Implement the `&` operator.

    When used with SQL expressions, results in an AND operation, equivalent to `and_()`, that is:

        a & b

    is equivalent to:

        from sqlalchemy import and_
        and_(a, b)

    Care should be taken when using `&` regarding operator precedence; the `&` operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

        (a == 2) & (b == 4)

  `__delattr__`
    inherited from the `__delattr__` attribute of `object`

    x.__delattr__(‘name’) <==> del x.name

  `__div__`(other)

    Implement the `/` operator.

    In a column context, produces the clause `a / b`.

  `__eq__`(other)

    Implement the `==` operator.

    In a column context, produces the clause `a = b`. If the target is `None`, produces `a IS NULL`.

  `__format__`()
    inherited from the `__format__()` method of `object`

    default object formatter

  `__ge__`(other)

    Implement the `>=` operator.

    In a column context, produces the clause `a >= b`.

  `__getattribute__`
    inherited from the `__getattribute__` attribute of `object`

    x.__getattribute__(‘name’) <==> x.name

  `__getitem__`(index)

    Implement the [] operator.

    This can be used by some database-specific types such as Postgresql ARRAY and HSTORE.

  `__gt__`(other)

    Implement the `>` operator.

    In a column context, produces the clause `a > b`.

  `__hash__`

    x.__hash__() <==> hash(x)

  `__init__`
    inherited from the `__init__` attribute of `object`

    x.__init__(...) initializes x; see help(type(x)) for signature

  `__invert__`()
    inherited from the `__invert__()` method of `Operators`

    Implement the `~` operator.

    When used with SQL expressions, results in a NOT operation, equivalent to `not_()`, that is:

        ~a

    is equivalent to:

        from sqlalchemy import not_
        not_(a)

  `__le__`(other)

    Implement the `<=` operator.

    In a column context, produces the clause `a <= b`.

  `__lshift__`(other)

    implement the << operator.

    Not used by SQLAlchemy core, this is provided for custom operator systems which want to use << as an extension point.

  `__lt__`(other)

    Implement the `<` operator.

    In a column context, produces the clause `a < b`.

  `__mod__`(other)

    Implement the `%` operator.

    In a column context, produces the clause `a % b`.

  `__mul__`(other)

    Implement the `*` operator.

    In a column context, produces the clause `a * b`.

  `__ne__`(other)

    Implement the `!=` operator.

    In a column context, produces the clause `a != b`. If the target is `None`, produces `a IS NOT NULL`.

  `__neg__`()

    Implement the `-` operator.

    In a column context, produces the clause `-a`.

  static `__new__`(S, ...) → a new object with type S, a subtype of T
    inherited from the `__new__()` method of `object`
  `__or__`(other)
    inherited from the `__or__()` method of `Operators`

    Implement the `|` operator.

    When used with SQL expressions, results in an OR operation, equivalent to `or_()`, that is:

        a | b

    is equivalent to:

        from sqlalchemy import or_
        or_(a, b)

    Care should be taken when using `|` regarding operator precedence; the `|` operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

        (a == 2) | (b == 4)

  `__radd__`(other)

    Implement the `+` operator in reverse.

    See `ColumnOperators.__add__()`.

  `__rdiv__`(other)

    Implement the `/` operator in reverse.

    See `ColumnOperators.__div__()`.

  `__reduce__`()
    inherited from the `__reduce__()` method of `object`

    helper for pickle

  `__reduce_ex__`()
    inherited from the `__reduce_ex__()` method of `object`

    helper for pickle

  `__repr__`
    inherited from the `__repr__` attribute of `object`

    x.__repr__() <==> repr(x)

  `__rmul__`(other)

    Implement the `*` operator in reverse.

    See `ColumnOperators.__mul__()`.

  `__rshift__`(other)

    implement the >> operator.

    Not used by SQLAlchemy core, this is provided for custom operator systems which want to use >> as an extension point.

  `__rsub__`(other)

    Implement the `-` operator in reverse.

    See `ColumnOperators.__sub__()`.

  `__rtruediv__`(other)

    Implement the `//` operator in reverse.

    See `ColumnOperators.__truediv__()`.

  `__setattr__`
    inherited from the `__setattr__` attribute of `object`

    x.__setattr__(‘name’, value) <==> x.name = value

  `__sizeof__`() → int
    inherited from the `__sizeof__()` method of `object`

    size of object in memory, in bytes

  `__str__`
    inherited from the `__str__` attribute of `object`

    x.__str__() <==> str(x)

  `__sub__`(other)

    Implement the `-` operator.

    In a column context, produces the clause `a - b`.

  static `__subclasshook__`()
    inherited from the `__subclasshook__()` method of `object`

    Abstract classes can override this to customize issubclass().

    This is invoked early on by abc.ABCMeta.__subclasscheck__(). It should return True, False or NotImplemented. If it returns NotImplemented, the normal algorithm is used. Otherwise, it overrides the normal algorithm (and the outcome is cached).

  `__truediv__`(other)

    Implement the `//` operator.

    In a column context, produces the clause `a / b`.

  `__weakref__`
    inherited from the `__weakref__` attribute of `Operators`

    list of weak references to the object (if defined)

  `asc`()

    Produce a `asc()` clause against the parent object.

  `between`(cleft, cright)

    Produce a `between()` clause against the parent object, given the lower and upper range.

  `collate`(collation)

    Produce a `collate()` clause against the parent object, given the collation string.

  `concat`(other)

    Implement the ‘concat’ operator.

    In a column context, produces the clause `a || b`, or uses the `concat()` operator on MySQL.

  `contains`(other, **kwargs)

    Implement the ‘contains’ operator.

    In a column context, produces the clause `LIKE '%<other>%'`

  `desc`()

    Produce a `desc()` clause against the parent object.

  `distinct`()

    Produce a `distinct()` clause against the parent object.

  `endswith`(other, **kwargs)

    Implement the ‘endswith’ operator.

    In a column context, produces the clause `LIKE '%<other>'`

  `ilike`(other, escape=None)

    Implement the `ilike` operator.

    In a column context, produces the clause `a ILIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.ilike("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.ilike("foo/%bar", escape="/")

    See also

    `ColumnOperators.like()`

  `in_`(other)

    Implement the `in` operator.

    In a column context, produces the clause `a IN other`. “other” may be a tuple/list of column expressions, or a `select()` construct.

  `is_`(other)

    Implement the `IS` operator.

    Normally, `IS` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.isnot()`

  `isnot`(other)

    Implement the `IS NOT` operator.

    Normally, `IS NOT` is generated automatically when comparing to a value of `None`, which resolves to `NULL`. However, explicit usage of `IS NOT` may be desirable if comparing to boolean values on certain platforms.

    New in version 0.7.9.

    See also

    `ColumnOperators.is_()`

  `like`(other, escape=None)

    Implement the `like` operator.

    In a column context, produces the clause `a LIKE other`.

    E.g.:

        select([sometable]).where(sometable.c.column.like("%foobar%"))

    - Parameters: | other – expression to be compared escape – optional escape character, renders the `ESCAPE` keyword, e.g.:
          somecolumn.like("foo/%bar", escape="/")

    See also

    `ColumnOperators.ilike()`

  `match`(other, **kwargs)

    Implements the ‘match’ operator.

    In a column context, this produces a MATCH clause, i.e. `MATCH '<other>'`. The allowed contents of `other` are database backend specific.

  `notilike`(other, escape=None)

    implement the `NOT ILIKE` operator.

    This is equivalent to using negation with `ColumnOperators.ilike()`, i.e. `~x.ilike(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.ilike()`

  `notin_`(other)

    implement the `NOT IN` operator.

    This is equivalent to using negation with `ColumnOperators.in_()`, i.e. `~x.in_(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.in_()`

  `notlike`(other, escape=None)

    implement the `NOT LIKE` operator.

    This is equivalent to using negation with `ColumnOperators.like()`, i.e. `~x.like(y)`.

    New in version 0.8.

    See also

    `ColumnOperators.like()`

  `nullsfirst`()

    Produce a `nullsfirst()` clause against the parent object.

  `nullslast`()

    Produce a `nullslast()` clause against the parent object.

  `op`(opstring, precedence=0)
    inherited from the `op()` method of `Operators`

    produce a generic operator function.

    e.g.:

        somecolumn.op("*")(5)

    produces:

        somecolumn * 5

    This function can also be used to make bitwise operators explicit. For example:

        somecolumn.op('&')(0xff)

    is a bitwise AND of the value in `somecolumn`.

    Parameters: | operator – a string which will be output as the infix operator between this element and the expression passed to the generated function. precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of `0` is lower than all operators except for the comma (`,`) and `AS` operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators. New in version 0.8: - added the ‘precedence’ argument.

    See also

    Redefining and Creating New Operators

  `operate`(op, *other, **kwargs)
    inherited from the `operate()` method of `Operators`

    Operate on an argument.

    This is the lowest level of operation, raises `NotImplementedError` by default.

    Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding `ColumnOperators` to apply `func.lower()` to the left and right side:

        class MyComparator(ColumnOperators):
            def operate(self, op, other):
                return op(func.lower(self), func.lower(other))

    Parameters: | op – Operator callable. *other – the ‘other’ side of the operation. Will be a single scalar for most operations. **kwargs – modifiers. These may be passed by special operators such as `ColumnOperators.contains()`.

  `reverse_operate`(op, other, **kwargs)
    inherited from the `reverse_operate()` method of `Operators`

    Reverse operate on an argument.

    Usage is the same as `operate()`.

  `startswith`(other, **kwargs)

    Implement the `startwith` operator.

    In a column context, produces the clause `LIKE '<other>%'`

  `timetuple` = None

    Hack, allows datetime objects to be compared on the LHS.

class `sqlalchemy.sql.expression.` `Extract`(field, expr, **kwargs)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

class `sqlalchemy.sql.expression.` `False_`

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent the `false` keyword in a SQL statement.

  Public constructor is the `false()` function.

class `sqlalchemy.sql.expression.` `Label`(name, element, type_=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represents a column label (AS).

  Represent a label, as typically applied to any column-level element using the `AS` sql keyword.

  This object is constructed from the `label()` module level function as well as the `label()` method available on all `ColumnElement` subclasses.

class `sqlalchemy.sql.expression.` `Null`

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent the NULL keyword in a SQL statement.

  Public constructor is the `null()` function.

class `sqlalchemy.sql.expression.` `Over`(func, partition_by=None, order_by=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent an OVER clause.

  This is a special operator against a so-called “window” function, as well as any aggregate function, which produces results relative to the result set itself. It’s supported only by certain database backends.

class `sqlalchemy.sql.expression.` `TextClause`(text='', bind=None, bindparams=None, typemap=None, autocommit=None)

  Bases: `sqlalchemy.sql.expression.Executable`, `sqlalchemy.sql.expression.ClauseElement`

  Represent a literal SQL text fragment.

  Public constructor is the `text()` function.

class `sqlalchemy.sql.expression.` `Tuple`(*clauses, **kw)

  Bases: `sqlalchemy.sql.expression.ClauseList`, `sqlalchemy.sql.expression.ColumnElement`

class `sqlalchemy.sql.expression.` `True_`

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Represent the `true` keyword in a SQL statement.

  Public constructor is the `true()` function.

class `sqlalchemy.sql.operators.` `custom_op`(opstring, precedence=0)

  Represent a ‘custom’ operator.

  `custom_op` is normally instantitated when the `ColumnOperators.op()` method is used to create a custom operator callable. The class can also be used directly when programmatically constructing expressions. E.g. to represent the “factorial” operation:

      from sqlalchemy.sql import UnaryExpression
      from sqlalchemy.sql import operators
      from sqlalchemy import Numeric

      unary = UnaryExpression(table.c.somecolumn,
              modifier=operators.custom_op("!"),
              type_=Numeric)

class `sqlalchemy.sql.operators.` `Operators`

  Base of comparison and logical operators.

  Implements base methods `operate()` and `reverse_operate()`, as well as `__and__()`, `__or__()`, `__invert__()`.

  Usually is used via its most common subclass `ColumnOperators`.

  `__and__`(other)

    Implement the `&` operator.

    When used with SQL expressions, results in an AND operation, equivalent to `and_()`, that is:

        a & b

    is equivalent to:

        from sqlalchemy import and_
        and_(a, b)

    Care should be taken when using `&` regarding operator precedence; the `&` operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

        (a == 2) & (b == 4)

  `__invert__`()

    Implement the `~` operator.

    When used with SQL expressions, results in a NOT operation, equivalent to `not_()`, that is:

        ~a

    is equivalent to:

        from sqlalchemy import not_
        not_(a)

  `__or__`(other)

    Implement the `|` operator.

    When used with SQL expressions, results in an OR operation, equivalent to `or_()`, that is:

        a | b

    is equivalent to:

        from sqlalchemy import or_
        or_(a, b)

    Care should be taken when using `|` regarding operator precedence; the `|` operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

        (a == 2) | (b == 4)

  `__weakref__`

    list of weak references to the object (if defined)

  `op`(opstring, precedence=0)

    produce a generic operator function.

    e.g.:

        somecolumn.op("*")(5)

    produces:

        somecolumn * 5

    This function can also be used to make bitwise operators explicit. For example:

        somecolumn.op('&')(0xff)

    is a bitwise AND of the value in `somecolumn`.

    Parameters: | operator – a string which will be output as the infix operator between this element and the expression passed to the generated function. precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of `0` is lower than all operators except for the comma (`,`) and `AS` operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators. New in version 0.8: - added the ‘precedence’ argument.

    See also

    Redefining and Creating New Operators

  `operate`(op, *other, **kwargs)

    Operate on an argument.

    This is the lowest level of operation, raises `NotImplementedError` by default.

    Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding `ColumnOperators` to apply `func.lower()` to the left and right side:

        class MyComparator(ColumnOperators):
            def operate(self, op, other):
                return op(func.lower(self), func.lower(other))

    Parameters: | op – Operator callable. *other – the ‘other’ side of the operation. Will be a single scalar for most operations. **kwargs – modifiers. These may be passed by special operators such as `ColumnOperators.contains()`.

  `reverse_operate`(op, other, **kwargs)

    Reverse operate on an argument.

    Usage is the same as `operate()`.

class `sqlalchemy.sql.expression.` `UnaryExpression`(element, operator=None, modifier=None, type_=None, negate=None)

  Bases: `sqlalchemy.sql.expression.ColumnElement`

  Define a ‘unary’ expression.

  A unary expression has a single column expression and an operator. The operator can be placed on the left (where it is called the ‘operator’) or right (where it is called the ‘modifier’) of the column expression.

  `compare`(other, **kw)

    Compare this `UnaryExpression` against the given `ClauseElement`.